1. Field of the Invention
This invention generally relates to semiconductor manufacturing equipment and, more particularly, to a system and method used for the processing of semiconductor wafers.
2. Description of the Related Art
During the processing of semiconductor devices, it is highly desirable to accurately control the thermal treatment to which the devices are exposed during processing. In some instances, batches of devices, primarily wafers, are processed in a semiconductor processing furnace, which has a carefully controlled processing environment to effect the desired processes.
Unfortunately, it has been found that in most conventional vertically arranged furnaces, the desired temperature is obtained in the process tube by surrounding the tube with heating elements. In this arrangement radiation and convection are used to heat the process tube first, before the heat energy is transferred to the cooler wafers. Convective heating is usually not effective because the process tube is typically isolated. During low temperature wafer processing operations, this type of heating arrangement is usually very inefficient and time consuming. Further, in this type of arrangement, a separate cooling chamber or blower for fast cooling of the entire furnace, is typically required since, it is difficult and inefficient to lower the temperature of the entire furnace assembly between processing operations on different batches of wafers.
For the above reasons, what is needed is a system and method for isothermally distributing a temperature across the surface of a semiconductor device which provide an accurate dynamic control of the process temperature, without degradation in uniformity of the processed wafers.